Estimation of surface wind speeds using satellite‐borne radar measurements at normal incidence

The results of a study to determine the correlation of the surface scattering cross section per unit area at normal incidence σ°(0°) and 13.9 GHz with surface wind speed are presented. Comparing σ°(0°) measurements with ship reports of wind speed, it was found that an algorithm could be devised which is capable of producing wind speed estimates from σ°(0°) measurements to a precision of 2.6 m/s for winds in the range of 1–21 m/s. Correlations with buoy measurements in the range of 1–10 m/s show an rms precision of 2.1 m/s with the possibility of a slight bias in the ship report based algorithm. A study of σ°(0°)‐inferred wind speeds in relation to hindcast estimates shows a distinct tendency in the hindcast results to be biased toward the low side in the absence of sufficient ship reports of wind and pressure. The results of this study indicate that a short‐pulse radar altimeter can provide reasonably accurate estimates of surface wind speeds over a rather large range of wind speeds.